Bisazo compounds as charge generating materials

ABSTRACT

An electrophotographic photoconductor is disclosed, which comprises an electroconductive support and a photoconductive layer formed thereon comprising a bisazo pigment having the formula (I) serving as a charge generating material: ##STR1## wherein Ar represents a residual group of a coupler represented by ArH selected from the group consisting of: an aromatic hydrocarbon compound having a hydroxyl group, a heterocyclic compound having a hydroxyl group, an aromatic hydrocarbon compound having an amino group, a heterocyclic compound having an amino group, an aromatic hydrocarbon compound having a hydroxyl group and an amino group, a heterocyclic compound having a hydroxyl group and an amino group, an aliphatic compound having an enolic ketone group, and an aromatic hydrocarbon compound having an enolic ketone group. Further, charge generating materials and novel bisazo pigments for use in the electrophotographic photoconductor are disclosed.

This is a divisional of application Ser. No. 07/924, 581, filed on Aug.5, 1992, now U.S. Pat. No. 5,344,735, which is a continuation ofapplication Ser. No. 07/680,237, filed on Apr. 3, 1991, now abandoned,which is a Continuation of Application Ser. No. 07/341,111, filed onApr. 20, 1989, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to an electrophotographic photoconductorcomprising an electroconductive support and a photoconductive layercomprising a particular bisazo pigment as a charge generating materialwhich generates charge carriers when exposed to light.

Conventionally, a variety of inorganic and organic electrophotographicphotoconductors are known. As inorganic electrophotographicphotoconductors, there are known, for instance, a seleniumphotoconductor, a selenium-alloy photoconductor, and a zinc oxidephotoconductor which is prepared by sensitizing zinc oxide with asensitizer pigment and dispersing the same in a binder resin.Furthermore, as a representative example of organic electrophotographicphotoconductors, an electrophotographic photoconductor comprising acharge transporting complex of 2,4,7-trinitro-9-fluorenone andpoly-N-vinylcarbazole is known.

However, while these electrophotographic photoconductors have manyadvantages over other conventional electro-photographic photoconductors,they have several shortcomings from the viewpoint of practical use.

For instance, a selenium photoconductor, which is widely used atpresent, has the shortcomings that its manufacturing conditions aredifficult and, accordingly, its production cost is high, and it isdifficult to work it into the form of a belt due to its poorflexibility. Furthermore, it is so vulnerable to heat and mechanicalshocks that it must be handled with the utmost care.

In contrast to this, the zinc oxide photoconductor is inexpensive sinceit can be produced more easily than the selenium photoconductor.Specifically, it can be produced by simply coating inexpensive zincoxide particles on a support. However, it is poor in photosensitivity,surface smoothness, hardness, tensile strength and wear resistance.Therefore, it is not suitable for a photoconductor for use in plainpaper copiers in which the photoconductor is used in quick repetition.

The photoconductor employing the aforementioned complex of2,4,7-trinitro-9-fluorenone and poly-N-vinylcarbazole is also poor inphotosensitivity and therefore not suitable for practical use,particularly for a high speed copying machine.

Recently, extensive studies have been done on the electrophotographicphotoconductors in order to eliminate the above-mentioned shortcomingsof the conventional photoconductors. In particular, attention has beenfocused on a multi-layered type organic electrophotographicphotoconductor, each comprising an electroconductive support, a chargegeneration layer comprising an organic pigment formed on theelectroconductive support, and a charge transport layer comprising acharge transporting material formed on the charge generation layer,which are for use in plain paper copiers, since such multi-layered typeorganic photoconductors have high photosensitivity and stable chargingproperties when compared with the conventional organic photoconductors.As a matter of fact, several types of multi-layered type organicelectrophotographic photoconductors are being successfully used inpractice. Examples of the multi-layered type organic electrophotographicphotoconductors are as follows:

(1) A multi-layered type electrophotographic photoconductor whose chargegeneration layer is prepared by vacuum evaporation of a perylenederivative and whose charge transport layer comprises an oxadiazolederivative, disclosed in U.S. Pat. No. 3,871,882.

(2) A multi-layered type electrophotographic photoconductor whose chargegeneration layer comprises Chlorodiane Blue which is dispersed in anorganic amine solution and coated on an electroconductive support andwhose charge transport layer comprises a hydrazone derivative, disclosedin Japanese Patent publication No. 55-42380.

(3) A multi-layered type electrophotographic photoconductor whose chargegeneration layer comprises a distyrylbenzene type bisazo pigmentdispersed in an organic solvent and coated on an electroconductivesupport, and whose charge transport layer comprises a hydrazonecompound, disclosed in Japanese Laid-Open Patent Application No.55-84943.

(4) A multi-layered type electrophotographic photoconductor whose chargegeneration layer comprises a bisazo compound represented by thefollowing formula, disclosed in U.S. Pat. No. 4,486,519: ##STR2##

(5) A multi-layered type electrophotographic photoconductor whose chargegeneration layer comprises a bisazo compound represented by thefollowing formula, disclosed in Japanese Laid-Open Patent ApplicationNo. 62-273545: ##STR3##

As previously mentioned, these multi-layered type electrophotographicphotoconductors have many advantages over other electrophotographicphotoconductors, but at the same time, they have various shortcomings.

Specifically, the electrophotographic photoconductor (1) employing aperylene derivative and an oxadiazole derivative presents no problem foruse in an ordinary electrophotographic copying machine, but itsphotosensitivity is insufficient for use in a high-speedelectro-photographic copying machine. Furthermore, since the perylenederivative, which is a charge generating material and has the functionof controlling the spectral sensitivity of the photoconductor, does notnecessarily have spectral absorbance in the entire visible region, thisphotoconductor is not suitable for use in color copiers.

The electrophotographic photoconductor (2) employing Chlorodiane Blueand a hydrazone compound exhibits comparatively good photosensitivity.However, when preparing this photoconductor, an organic amine, forexample, ethylene diamine, which is difficult to handle, is necessary asa coating solvent for forming the charge generation layer.

The electrophotographic photoconductor (3) employing a distyryl benzenetype bisazo compound and a hydrazone compound have an advantage overother conventional electrophotographic photoconductors in that thecharge generation layer can be prepared easily by coating a dispersionof the bisazo pigment on an electroconductive support. However, thephotosensitivity of the photoconductor is too low to use as aphotoconductor for a high-speed electrophotographic copying machine.

Furthermore, recently there is a demand for a photoconductor for use inlaser printers, in particular, for a highly sensitive photoconductorhaving a photosensitivity in a semiconductor laser wavelength region.

Even the electrophotographic photoconductor (4) and employing thepreviously mentioned bisazo compound(s) show insufficient absorbancenear 780 nm of a semiconductor laser wavelength region.

Any of the above-mentioned photoconductors has too low aphotosensitivity to use in practice-for semiconductor laser.

SUMMARY OF THE INVENTION

It is therefore a first object of the present invention to provide anelectrophotographic photoconductor from which the above-mentionedconventional shortcomings are eliminated, and which has highphotosensitivity and uniform spectral absorbance not only in the entirevisible region, but also in the semiconductor laser wavelength region,and which gives rise to no difficulty in the production of theelectrophotographic photoconductor and is suitable for use in laserprinters.

A second object of the present invention is to provide charge generatingmaterials for use in the above-mentioned electrophotographicphotoconductor.

A third object of the present invention is to provide novel bisazocompounds employed as the above-mentioned charge generating materials.

The first object of the present invention is achieved by anelectrophotographic photoconductor comprising an electroconductivesupport and a photoconductive layer formed thereon comprising a bisazopigment having the formula (I) serving as a charge generating material:##STR4## wherein Ar represents a residual group of a coupler representedby ArH selected from the group consisting of: an aromatic hydrocarboncompound having a hydroxyl group, a heterocyclic compound having ahydroxyl group, an aromatic hydrocarbon compound having an amino group,a heterocyclic compound having an amino group, an aromatic hydrocarboncompound having a hydroxyl group and an amino group, a heterocycliccompound having a hydroxyl group and an amino group, an aliphaticcompound having an enolic ketone group, and an aromatic hydrocarboncompound having an enolic ketone group.

The second object of the present invention can be achieved by any of thefollowing three types of charging materials: ##STR5## wherein Ar in theformula (I) is ##STR6## wherein X represents --OH, ##STR7## or --NHSO₂--R³, wherein R¹ and R² each represent hydrogen, an unsubstituted orsubstituted alkyl group; and R³ represents an unsubstituted orsubstituted alkyl group or an unsubstituted or substituted aryl group;

Y¹ represents hydrogen, a halogen, an unsubstituted or substituted alkylgroup, an unsubstituted or substituted alkoxyl group, a carboxyl group,a sulfo group, an unsubstituted or substituted sulfamoyl group, or##STR8## wherein R⁴ represents hydrogen, an unsubstituted or substitutedalkyl group, or an unsubstituted or substituted phenyl group; and Y²represents an unsubstituted or substituted cyclic hydrocarbon group, oran unsubstituted or substituted heterocyclic group, or ##STR9## whereinR⁵ represents an unsubstituted or substituted cyclic hydrocarbon group,an unsubstituted or substituted heterocyclic group, or an unsubstitutedor substituted styryl group; and R⁶ represents hydrogen, an alkyl group,or an unsubstituted or substituted phenyl group, or R⁵ and R⁶ may forman unsubstituted or substituted ring in combination with a carbon atomlinked thereto;

Z represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group; n is an integerof 1 or 2; and m is an integer of 1 or 2. ##STR10## wherein Ar is##STR11## wherein X represents --OH, ##STR12## or --NHSO₂ --R³, whereinR¹ and R² each represent hydrogen, an unsubstituted or substituted alkylgroup; and R³ represents an unsubstituted or substituted alkyl group oran unsubstituted or substituted aryl group;

Y¹ represents hydrogen, a halogen, an unsubstituted or substituted alkylgroup, an unsubstituted or substituted alkoxyl-group, a carboxyl group-asulfo group an unsubstituted or substituted sulfamoyl group, or##STR13## wherein R⁴ represents hydrogen, an unsubstituted orsubstituted alkyl group, or an unsubstituted or substituted phenylgroup; and Y² represents an unsubstituted or substituted cyclichydrocarbon group, or an unsubstituted or substituted heterocyclicgroup, or ##STR14## wherein R⁵ represents an unsubstituted orsubstituted cyclic hydrocarbon group, an unsubstituted or substitutedheterocyclic group, or an unsubstituted or substituted styryl group; andR⁶ represents hydrogen, an alkyl group, or an unsubstituted orsubstituted phenyl group,

R⁵ R⁶ may form an substituted or substituted ring in combination with acarbon atom linked thereto; and

Z represents an unsubstituted or substituted cyclic hydrocarbon group oran unsubstituted or substituted heterocyclic group. ##STR15## wherein Aris ##STR16## wherein X represents --OH, ##STR17## or --NHSO₂ --R³,wherein R¹ and R² each represent hydrogen, an unsubstituted orsubstituted alkyl group; and R³ represents an unsubstituted orsubstituted alkyl group or an unsubstituted or substituted aryl group;

Y¹ represents hydrogen, a halogen, a substituted or unsubstituted alkylgroup, an unsubstituted or substituted alkoxyl group, a carboxyl group,a sulfo group, a substituted or unsubstituted sulfamoyl group, or##STR18## wherein R⁴ represents hydrogen, an unsubstituted or substitutealkyl group, or an unsubstituted or substituted phenyl group; and Y²represents an unsubstituted or substituted cyclic hydrocarbon group, oran unsubstituted or substituted heterocyclic group, or ##STR19## whereinR⁵ represents an unsubstituted or substituted cyclic hydrocarbon group,an unsubstituted or substituted heterocyclic group, or an unsubstitutedor substituted styryl group; and R⁶ represents hydrogen, an alkyl group,or an unsubstituted or substituted phenyl group, or R⁵ and R⁶ may forman unsubstituted or substituted ring in combination with a carbon atomlinked thereto; and

Z represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group.

The third object of the present invention can be achieved by a bisazocompound having the formula: ##STR20## wherein Ar represents ##STR21##wherein Y represents a methoxy carbonyl group; an N,N-dimethyl carbamoylgroup; --CONH--Y¹ in which Y¹ represents an unsubstituted or substitutedhydrocarbon group, or an unsubstituted or substituted heterocyclicgroup; or --CONH═CH--Y² in which Y² represents an unsubstituted orsubstituted hydrocarbon group, or an unsubstituted or substitutedheterocyclic group; and Z represents a benzene ring, a naphthalene ring,or a carbazole ring each of which ring may have a substituent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 10 are IR spectra of bisazo pigments according to the presentinvention.

FIG. 11 is a schematic cross-sectional view of an example of anelectrophotographic photoconductor according to the present invention.

FIG. 12 is a schematic cross-sectional view of another example of anelectrophotographic photoconductor according to the present invention.

FIG. 13 is a graph showing the relationship between the spectralreflectance and the wavelength, bisazo pigments for use in the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The electrophotographic photoconductor according to the presentinvention comprises an electroconductive support and a photoconductivelayer formed thereon comprising a bisazo pigment having the formula (I)serving as a charge generating material: ##STR22## wherein Ar representsa residual group of a coupler represented by ArH selected from the groupconsisting of: an aromatic hydrocarbon compound having a hydroxyl group,a heterocyclic compound having a hydroxyl group, an aromatic hydrocarboncompound having an amino group, a heterocyclic compound having an aminogroup, an aromatic hydrocarbon compound having a hydroxyl group and anamino group, a heterocyclic compound having a hydroxyl group and anamino group, an aliphatic compound having an enolic ketone group, and anaromatic hydrocarbon compound having an enolic ketone group.

Preferable examples of the residual group represented by Ar of a couplerrepresented by ArH for the preparation of the above bisazo pigment areas follows: ##STR23## wherein X represents --OH, ##STR24## or --NHSO₂--R³, wherein R¹ and R² each represent hydrogen, an unsubstituted orsubstituted alkyl group; and R³ represents an unsubstituted or ansubstituted alkyl group or an unsubstituted or substituted aryl-group;Y¹ represents hydrogen, a halogen, an un substituted or substitutedalkyl group, an unsubstituted or substituted alkoxyl group, a carboxylgroup, a sulfo group, an unsubstituted or substituted sulfamoyl group,or ##STR25## wherein R⁴ represents hydrogen, an unsubstituted orsubstituted alkyl group, or an unsubstituted or substituted phenylgroup; and Y² represents an unsubstituted or substituted cyclichydrocarbon group, or an unsubstituted or substituted heterocyclicgroup, or ##STR26## wherein R⁵ represents an unsubstituted orsubstituted cyclic hydrocarbon group, an unsubstituted or substituteheterocyclic group, or an unsubstituted or substituted styryl group; andR⁶ represents hydrogen, an alkyl group, or an unsubstituted orsubstituted phenyl group, or R⁵ and R⁶ may form an unsubstituted orsubstituted ring in combination with a carbon atom linked thereto;

z represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group; n is an integerof 1 or 2; and m is an integer of 1 or 2. ##STR27## wherein X represents--OH, ##STR28## or --NHSO₂ --R³, wherein R¹ and R² each representhydrogen, an unsubstituted or substituted alkyl group; and R³ representsan unsubstituted or substituted alkyl group or an unsubstituted orsubstituted aryl group; and

R⁷ represents an unsubstituted or substituted hydrocarbon group.##STR29## wherein X represents --OH, ##STR30## or --NHSO₂ --R³, whereinR¹ and R² each represent hydrogen, an unsubstituted or unsubstitutedalkyl group; and R³ represents an unsubstituted or substituted alkylgroup or an unsubstituted or substituted aryl group; and R⁸ representsan alkyl group, a carbamoyl group, a carboxyl group or ester groupthereof; and Ar¹ represents an unsubstituted or substituted cyclichydrocarbon group. ##STR31## wherein X represents --OH, ##STR32## or--NHSO₂ --R³, wherein R¹ and R² each represent hydrogen, anunsubstituted or substituted alkyl group; and R³ represents anunsubstituted or substituted alkyl group or an unsubstituted orsubstituted aryl group; and

R⁹ represents hydrogen or an unsubstituted or substituted hydrocarbongroup; and Ar² represents an unsubstituted or substituted cyclichydrocarbon group. ##STR33## Y¹ represents hydrogen, a halogen, anunsubstituted or substituted alkyl group, an unsubstituted orsubstituted alkoxyl group, a carboxyl group, a sulfo group, anunsubstituted or substituted sulfamoyl group, or ##STR34## wherein R⁴represents hydrogen, an unsubstituted or substituted alkyl group, or anunsubstituted or substituted phenyl group; and Y² represents anunsubstituted or substituted cyclic hydrocarbon group, or anunsubstituted or substituted heterocyclic group, or ##STR35## wherein R⁵represents an unsubstituted or substituted cyclic hydrocarbon group, anunsubstituted or substituted heterocyclic group, or an unsubstituted orsubstituted styryl group; and R⁶ represents hydrogen, an alkyl group, oran unsubstituted or substituted phenyl group, or R⁵ and R⁶ may form aring in combination with a carbon atom linked thereto; and

Z represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group. ##STR36## whereinZ represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group; Y² represents anunsubstituted or substituted cyclic hydrocarbon group, or anunsubstituted or substituted heterocyclic group; and R² representshydrogen, an unsubstituted or substituted alkyl group, or unsubstitutedor substituted phenyl group. ##STR37## wherein Z represents anunsubstituted or substituted cyclic hydrocarbon group, or anunsubstituted or substituted heterocyclic group; R² represents hydrogen,an unsubstituted or substituted alkyl group, or an unsubstituted orsubstituted phenyl group; and R¹⁰ represents a group selected from thegroup consisting of an alkyl group having 1 to 4 carbon atoms, analkoxyl group having 1 to 4 carbon atoms, a halogen, a dialkylaminogroup, a diaralkylamino group, a halomethyl group, a nitro group, acyano group, a carboxyl group or ester group, a hydroxyl group and asulfonate group. ##STR38## wherein Z represents an unsubstituted orsubstituted cyclic hydrocarbon group, or an unsubstituted or substitutedheterocyclic group; R⁵ represents an unsubstituted or substituted cyclichydrocarbon group, an unsubstituted or substituted heterocyclic group,or an unsubstituted or substituted styryl group; and R⁶ representshydrogen, an alkyl group, or an unsubstituted or substituted phenylgroup, or R⁵ and R⁶ may form an unsubstituted or substituted ring incombination with a carbon atom linked thereto. ##STR39## wherein R¹represents hydrogen, an alkyl group such as a methyl group and an ethylgroup; an alkoxyl group such as a methoxy group and an ethoxy group; anitro group; or a halogen; R² represents an alkyl group such as a methylgroup and an ethyl group; an alkoxyl group such as a methoxy group andan ethoxy group; a halogen; or a nitro group; and m and n each representan integer of 1 to 3.

Of the above mentioned residual groups represented by Ar, the residualgroup represented by the formulas (I-12) and (I-13) are most preferablefor use in the present invention.

In the above examples of the residual group represented by Ar in theformulas (I-1) to (I-4) and (I-10) to (I-13), as the cyclic hydrocarbongroup represented by Z, a benzene ring and a naphthalene ring, which mayhave a substituent selected from the group consisting of a halogen, analkyl group, and an alkoxyl group, are preferable for use in the presentinvention.

Further, as the heterocyclic group represented by Z, an indole ring, acarbazole ring and a benzofuran ring, which may have a substituentselected from the group consisting of a halogen, an alkyl group, and analkoxyl group, are preferable for use in the present invention.

As the cyclic hydrocarbon group represented by Y² or R⁵, a phenyl group,a naphthyl group, an anthryl group, and a pyrenyl group, which may havea substituent selected from the group consisting of an alkyl grouphaving 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms,a halogen, a dialkylamino group, a diaralkylamino group, a halomethylgroup, a nitro group, a cyano group, a carboxyl group or ester group, ahydroxyl group and a sulfonate group, are preferable for use in thepresent invention.

As the heterocyclic group represented by Y² or R⁵, a pyridyl group, athienyl group, a furyl group, anindolyl group, a benzofuranyl group, acarbazolyl group and a dibenzofuranyl group, which may have asubstituent selected from the group consisting of an alkyl group having1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, ahalogen, a dialkylamino group, a diaralkylamino group, a halomethylgroup, a nitro group, a cyano group, a carboxyl group or ester group, ahydroxyl group and a sulfonate group, are preferable for use in thepresent invention.

As the ring formed by R⁵ and R⁶, a fluorene ring which may have asubstituent selected from the group consisting of an alkyl group having1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, ahalogen, a dialkylamino group, a diaralkylamino group, a halomethylgroup, a nitro group, a cyano group, a carboxyl group or ester group, ahydroxyl group and a sulfonate group, are preferable for use in thepresent invention.

A preferable substituent of the phenyl group represented by R⁴ is ahalogen such as bromide.

In the examples of the residual group represented by Ar in the formulas(I-5) and (I-6), as the hydrocarbon group represented by R⁷, an alkylgroup having 1 to 4 carbon atoms, an aralkyl group, and an aryl group,which aralkyl group and aryl group may have a substituent selected fromthe group consisting of an alkyl group having 1 to 4 carbon atoms, analkoxyl group having 1 to 4 carbon atoms, a halogen, a hydroxyl groupand a nitro group, are preferable for use in the present invention.

In the examples of the residual group represented by Ar in the formula(I-7), as the cyclic hydrocarbon group represented by Ar¹ a phenyl groupand a naphthyl group which may have a substituent selected from thegroup consisting of an alkyl group having 1 to 4 carbon atoms, analkoxyl group having 1 to 4 carbon atoms, a halogen, a cyano group, anda dialkylamino group, are preferable for use in the present invention.

In the examples of the residual group represented by Ar in the formulas(I-8) and (I-9), as the hydrocarbon group represented by R⁹, an alkylgroup having 1 to 4 carbon atoms, an aralkyl group, and an aryl group,which aralkyl group and aryl group may have a substituent selected fromthe group consisting of an alkyl group having 1 to 4 carbon atoms, analkoxyl group having 1 to 4 carbon atoms, a halogen, a hydroxyl groupand a nitro group, are preferable for use in the present invention.

Further as the cyclic hydrocarbon group represented by Ar², a phenylgroup and a naphthyl group which may have a substituent selected fromthe group consisting of an alkyl group having 1 to 4 carbon atoms analkoxyl group having 1 to 4 carbon atoms, a halogen, a cyano group, anda dialkylamino group, are preferable for use in the present invention.

The charge generating materials for use in the present invention arepreferably bisazo compounds having the following general formula:##STR40## wherein Ar in the formula (I) is ##STR41## wherein Xrepresents --OH, ##STR42## or --NHSO₂ --R³, wherein R¹ and R² eachrepresent hydrogen, an unsubstituted or substituted alkyl group; and R³represents an unsubstituted or substituted alkyl group or anunsubstituted or substituted aryl group;

Y¹ represents hydrogen, a halogen, an unsubstituted or substituted alkylgroup, an unsubstituted or substituted alkoxyl group, a carboxyl group,a sulfo group, an unsubstituted or substituted sulfamoyl group, or##STR43## wherein R⁴ represents hydrogen, an unsubstituted orsubstituted alkyl group, or an unsubstituted or substituted phenylgroup; and Y² represents an unsubstituted or substituted cyclichydrocarbon group, or an unsubstituted or substituted heterocyclicgroup, or ##STR44## wherein R⁵ represents an unsubstituted orsubstituted cyclic hydrocarbon group, an unsubstituted or substitutedheterocyclic group, or an unsubstituted or substituted styryl group; andR⁶ represents hydrogen, an alkyl group, or an unsubstituted orsubstituted phenyl group, or R⁵ and R⁶ may form an unsubstituted orsubstituted ring in combination with a carbon atom linked thereto;

Z represents an unsubstituted or substituted cyclic hydrocarbon group,or an unsubstituted or substituted heterocyclic group; n is an integerof 1 or 2; and m is an integer of 1 or 2.

The bisazo compounds for use in the present invention are bisazocompounds have the following general formula: ##STR45## wherein Arrepresents ##STR46## wherein Y represents a methoxy carbonyl group anN,N-dimethyl carbamoyl group; --CONH--Y¹ in which Y¹ represents anunsubstituted or substituted hydrocarbon group, or an unsubstituted orsubstituted heterocyclic group; or --CONH═CH--Y² in which Y² representsan unsubstituted or substituted hydrocarbon group, or an unsubstitutedor substituted heterocyclic group; and Z represents a benzene ring, anaphthalene ring, or a carbazole ring each of which ring may have asubstituent.

In the above, as preferable substituents of the rings represented by Zare a halogen, an alkyl group, and an alkoxyl group. Preferablehydrocarbon groups represented by Y¹ are a phenyl group which may have asubstituent selected from the group consisting of an alkyl group, analkoxyl group, a hydroxyl group, a dialkylamino group, a halogen, anitro group, a phenylamino group and a phenylcarbamoyl group; a naphthylgroup which may have a substituent selected from the group consisting ofan alkyl group, a halogen, a hydroxyl group, a nitro group and analkoxyl group; a carbazolyl group; and ##STR47##

Preferable hydrocarbon groups represented by Y² are a phenyl group and anaphthyl group, which may have a substituent selected from the groupconsisting of an alkyl group, an alkoxyl group, a halogen, a hydroxylgroup and a nitro group; and an anthryl group.

Representative examples of the bisazo pigment for use in the presentinvention are in the following Table 1.

                  TABLE 1                                                         ______________________________________                                         ##STR48##                                                                    No.  Ar                                                                       ______________________________________                                              ##STR49##                                                               2                                                                                   ##STR50##                                                               3                                                                                   ##STR51##                                                               4                                                                                   ##STR52##                                                               5                                                                                   ##STR53##                                                               6                                                                                   ##STR54##                                                               7                                                                                   ##STR55##                                                               8                                                                                   ##STR56##                                                               9                                                                                   ##STR57##                                                               10                                                                                  ##STR58##                                                               11                                                                                  ##STR59##                                                               12                                                                                  ##STR60##                                                               13                                                                                  ##STR61##                                                               14                                                                                  ##STR62##                                                               15                                                                                  ##STR63##                                                               16                                                                                  ##STR64##                                                               17                                                                                  ##STR65##                                                               18                                                                                  ##STR66##                                                               19                                                                                  ##STR67##                                                               20                                                                                  ##STR68##                                                               21                                                                                  ##STR69##                                                               22                                                                                  ##STR70##                                                               23                                                                                  ##STR71##                                                               24                                                                                  ##STR72##                                                               25                                                                                  ##STR73##                                                               26                                                                                  ##STR74##                                                               27                                                                                  ##STR75##                                                               28                                                                                  ##STR76##                                                               29                                                                                  ##STR77##                                                               30                                                                                  ##STR78##                                                               31                                                                                  ##STR79##                                                               32                                                                                  ##STR80##                                                               33                                                                                  ##STR81##                                                               34                                                                                  ##STR82##                                                               35                                                                                  ##STR83##                                                               36                                                                                  ##STR84##                                                               37                                                                                  ##STR85##                                                               38                                                                                  ##STR86##                                                               39                                                                                  ##STR87##                                                               40                                                                                  ##STR88##                                                               41                                                                                  ##STR89##                                                               42                                                                                  ##STR90##                                                               43                                                                                  ##STR91##                                                               44                                                                                  ##STR92##                                                               45                                                                                  ##STR93##                                                               46                                                                                  ##STR94##                                                               47                                                                                  ##STR95##                                                               48                                                                                  ##STR96##                                                               49                                                                                  ##STR97##                                                               50                                                                                  ##STR98##                                                               51                                                                                  ##STR99##                                                               52                                                                                  ##STR100##                                                              53                                                                                  ##STR101##                                                              54                                                                                  ##STR102##                                                              55                                                                                  ##STR103##                                                              56                                                                                  ##STR104##                                                              57                                                                                  ##STR105##                                                              58                                                                                  ##STR106##                                                              59                                                                                  ##STR107##                                                              60                                                                                  ##STR108##                                                              61                                                                                  ##STR109##                                                              62                                                                                  ##STR110##                                                              63                                                                                  ##STR111##                                                              64                                                                                  ##STR112##                                                              65                                                                                  ##STR113##                                                              66                                                                                  ##STR114##                                                              67                                                                                  ##STR115##                                                              68                                                                                  ##STR116##                                                              69                                                                                  ##STR117##                                                              70                                                                                  ##STR118##                                                              71                                                                                  ##STR119##                                                              72                                                                                  ##STR120##                                                              73                                                                                  ##STR121##                                                              74                                                                                  ##STR122##                                                              75                                                                                  ##STR123##                                                              76                                                                                  ##STR124##                                                              77                                                                                  ##STR125##                                                              78                                                                                  ##STR126##                                                              79                                                                                  ##STR127##                                                              80                                                                                  ##STR128##                                                              81                                                                                  ##STR129##                                                              82                                                                                  ##STR130##                                                              83                                                                                  ##STR131##                                                              84                                                                                  ##STR132##                                                              85                                                                                  ##STR133##                                                              86                                                                                  ##STR134##                                                              87                                                                                  ##STR135##                                                              88                                                                                  ##STR136##                                                              89                                                                                  ##STR137##                                                              90                                                                                  ##STR138##                                                              91                                                                                  ##STR139##                                                              92                                                                                  ##STR140##                                                              93                                                                                  ##STR141##                                                              94                                                                                  ##STR142##                                                              95                                                                                  ##STR143##                                                              96                                                                                  ##STR144##                                                              97                                                                                  ##STR145##                                                              98                                                                                  ##STR146##                                                              99                                                                                  ##STR147##                                                              100                                                                                 ##STR148##                                                              101                                                                                 ##STR149##                                                              102                                                                                 ##STR150##                                                              103                                                                                 ##STR151##                                                              104                                                                                 ##STR152##                                                              105                                                                                 ##STR153##                                                              106                                                                                 ##STR154##                                                              107                                                                                 ##STR155##                                                              108                                                                                 ##STR156##                                                              109                                                                                 ##STR157##                                                              110                                                                                 ##STR158##                                                              111                                                                                 ##STR159##                                                              112                                                                                 ##STR160##                                                              113                                                                                 ##STR161##                                                              114                                                                                 ##STR162##                                                              115                                                                                 ##STR163##                                                              116                                                                                 ##STR164##                                                              117                                                                                 ##STR165##                                                              118                                                                                 ##STR166##                                                              119                                                                                 ##STR167##                                                              120                                                                                 ##STR168##                                                              121                                                                                 ##STR169##                                                              122                                                                                 ##STR170##                                                              123                                                                                 ##STR171##                                                              124                                                                                 ##STR172##                                                              125                                                                                 ##STR173##                                                              126                                                                                 ##STR174##                                                              127                                                                                 ##STR175##                                                              128                                                                                 ##STR176##                                                              129                                                                                 ##STR177##                                                              130                                                                                 ##STR178##                                                              131                                                                                 ##STR179##                                                              132                                                                                 ##STR180##                                                              133                                                                                 ##STR181##                                                              134                                                                                 ##STR182##                                                              135                                                                                 ##STR183##                                                              136                                                                                 ##STR184##                                                              137                                                                                 ##STR185##                                                              138                                                                                 ##STR186##                                                              139                                                                                 ##STR187##                                                              140                                                                                 ##STR188##                                                              141                                                                                 ##STR189##                                                              142                                                                                 ##STR190##                                                              143                                                                                 ##STR191##                                                              144                                                                                 ##STR192##                                                              145                                                                                 ##STR193##                                                              146                                                                                 ##STR194##                                                              147                                                                                 ##STR195##                                                              148                                                                                 ##STR196##                                                              149                                                                                 ##STR197##                                                              150                                                                                 ##STR198##                                                              151                                                                                 ##STR199##                                                              152                                                                                 ##STR200##                                                              153                                                                                 ##STR201##                                                              154                                                                                 ##STR202##                                                              155                                                                                 ##STR203##                                                              156                                                                                 ##STR204##                                                              157                                                                                 ##STR205##                                                              158                                                                                 ##STR206##                                                              159                                                                                 ##STR207##                                                              160                                                                                 ##STR208##                                                              161                                                                                 ##STR209##                                                              162                                                                                 ##STR210##                                                              163                                                                                 ##STR211##                                                              164                                                                                 ##STR212##                                                              165                                                                                 ##STR213##                                                              166                                                                                 ##STR214##                                                              167                                                                                 ##STR215##                                                              168                                                                                 ##STR216##                                                              169                                                                                 ##STR217##                                                              170                                                                                 ##STR218##                                                              171                                                                                 ##STR219##                                                              172                                                                                 ##STR220##                                                              173                                                                                 ##STR221##                                                              174                                                                                 ##STR222##                                                              175                                                                                 ##STR223##                                                              176                                                                                 ##STR224##                                                              177                                                                                 ##STR225##                                                              178                                                                                 ##STR226##                                                              179                                                                                 ##STR227##                                                              180                                                                                 ##STR228##                                                              181                                                                                 ##STR229##                                                              182                                                                                 ##STR230##                                                              183                                                                                 ##STR231##                                                              184                                                                                 ##STR232##                                                              185                                                                                 ##STR233##                                                              186                                                                                 ##STR234##                                                              187                                                                                 ##STR235##                                                              188                                                                                 ##STR236##                                                              189                                                                                 ##STR237##                                                              190                                                                            ##STR238##                                                                   191                                                                                 ##STR239##                                                              192                                                                                 ##STR240##                                                              193                                                                            ##STR241##                                                                   194                                                                                 ##STR242##                                                              195                                                                                 ##STR243##                                                              196                                                                                 ##STR244##                                                              197                                                                                 ##STR245##                                                              198                                                                                 ##STR246##                                                              199                                                                                 ##STR247##                                                              200                                                                                 ##STR248##                                                              201                                                                                 ##STR249##                                                              202                                                                                 ##STR250##                                                              203                                                                                 ##STR251##                                                              204                                                                                 ##STR252##                                                              205                                                                                 ##STR253##                                                              206                                                                                 ##STR254##                                                              207                                                                                 ##STR255##                                                              208                                                                                 ##STR256##                                                              209                                                                                 ##STR257##                                                              210                                                                                 ##STR258##                                                              211                                                                                 ##STR259##                                                              212                                                                                 ##STR260##                                                              213                                                                                 ##STR261##                                                              214                                                                                 ##STR262##                                                              ______________________________________                                    

The bisazo pigment of the above-mentioned formula for use in the presentinvention can be obtained by a coupling reaction of a bis(diazonium)saltof general formula (II-1) with a coupler of the general formula (II-2).##STR263## wherein X represents an anionic functional group.

    Ar--H                                                      (II-2)

wherein Ar is the same as previously defined in the general formula(II).

Specific examples of the anionic functional group represented by X inthe formula (XV) include Cl.sup.⊖, Br.sup.⊖, I.sup.⊖, BF₄.sup.⊖,PF₆.sup.⊖, B(C₆ H₅)₄.sup.⊖, ClO₄.sup.⊖, SO₄ ²⊖, ##STR264## AsF₆.sup.⊖and SbF₆.sup.⊖. Among the above anionic functional groups BF₄.sup.⊖ ispreferable for the preparation of the bisazo pigments.

The bisazo pigment of the formula (II) is prepared as follows:

The bis(diazonium)salt of the formula (II-1), used as a startingmaterial for the preparation of the bisazo pigment, can be obtained bydiazotization of 1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene(hereinafater referred to as the diamino compound) which is obtained byreduction of 1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene (hereinafterreferred to as the dinitro compound). The dinitro compound and thediamino compound are both novel materials.

To prepare the dinitro compound necessary for the synthesis of thebisazo pigment for use in the present invention, Witting reaction isinitiated, for example, by subjecting 1,4-bis(triphenylphosphoniumbromide)-2-butene and 4-nitrocinnamaldehyde to condensation in thepresence of a basic catalyst. The dinitro compound produced by theWitting reaction has a moiety of 3-monocis form or 3,7-dicis form, butcan be converted into a trans form as a whole in such a manner that thecrude or purified product of this dinitro compound is heated togetherwith a small amount of iodine which serves as a catalyst for thereaction in an aromatic hydrocarbon solvent such as toluene and xylene.Preparation of 1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene isdescribed in detail in a Japanese Patent Application filed on Apr. 20,1988 by the same inventors as those of the present invention, entitled"1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene and manufacturing methodthereof".

The thus obtained dinitro compound is reduced by heating it to 70° to120° C. using a reducing agent such as iron-hydrochloric acid andstannous chloride-hydrochloric acid, so that the diamino Compound isprepared. This reduction is completed in 0.5 to 3 hours. It ispreferable that such reduction be carried out in an organic solvent suchas N,N-dimethylformamide when iron-hydrochloric acid is employed as thereducing agent. The preparation of1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene is described in detail ina Japanese Patent Application filed on Apr. 20, 1988 by the sameinventors as those of the present invention, entitled"1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene and manufacturing methodthereof".

In the next step, diazotization of the above-prepared diamino compoundis performed by dispersing the diamino compound in an inorganic acidsuch as hydrochloric acid or sulphuric acid and adding sodium nitrite tothis dispersion, with the temperature maintained at -10° to 20° C. Thisdisazotization is completed in about 0.5 to 3 hours.

Through the above-mentioned series of the reaction, thebis(diazonium)salt of the general formula (II-1) can be obtained.Alternatively, by adding an aqueous solution of borofluoric acid orsodium borofluoride to the above disazotization reaction mixture, thebis(diazonium)salt can also be obtained. Preparation ofbis(diazonium)salt is described in detail in a Japanese PatentApplication filed on Apr. 20, 1988 by the same inventors as those of thepresent invention, entitled "Bis(diazonium) salt and manufacturingmethod thereof".

In order to obtain the bisazo pigment for use in the present invention,the above-prepared bis(diazonium)salt is isolated from the reactionmixture and dissolved together with the coupler of the general formula(XVI) in an organic solvent such as N,N-dimethylformamide and dimethylsulfoxide. To this solution, an alkaline aqueous solution such as anaqueous solution of sodium acetate is added dropwise, with thetemperature maintained at about -10° to 40° C., to initiate the couplingreaction. This coupling reaction is completed in about 5 minutes to 3hours. After the completion of the coupling reaction, the resultingcrystals are separated from the reaction solution by filtration, andwashed with water and/or an organic solvent, or recrystallized to purifythe obtained bisazo compound. Alternatively, the bisazo compound can beobtained by allowing the above-prepared diazotization reaction solutionto react with the coupler.

The present invention will now be explained by referring to thefollowing synthesis examples of the bisazo pigment.

Synthesis Example 1

[Preparation of 1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene]

In a stream of a nitrogen gas, 259 g of 1,4-bis(triphenylphosphoniumbromide)-2-butene was dissolved in 3 l of dry methanol. To thissolution, 130.5 g of 4-nitrocinnamaldehyde was added, and this mixturewas stirred for 30 minutes at room temperature. After the addition of4-nitrocinnamaldehyde, 32.0 g of lithium methoxide was further added tothe above mixture for 4 hours at 23° C. to 27° C. on a water bath. Afterstirred for 10 hours at room temperature, the thus prepared reactionmixture was diluted with 1 l of water, washed with water and then withmethanol, and dried, so that 120.9 g of a crude product in the form ofdark red powder was obtained.

The thus obtained crude product was added to 2.5 l of toluene togetherwith 2.42 g of iodine, and the mixture was stirred for 20 hours underapplication of heat, with the temperature of the reaction mixturemaintained at 86° C. to 90° C. This reaction mixture was cooled to roomtemperature, washed with toluene, and dried, whereby 113.6 g of apowdery dark red product was obtained in an 86.5% yield.

Finally, the crude product was recrystallized from dimethylformamide,whereby highly purified 1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaenewas obtained in the form of dark red needles. The melting point of theproduct was 241.5° to 242.5° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 70.57        4.86   7.48                                           Found      70.75        4.80   7.24                                           ______________________________________                                    

The above calculation was based on the formula for1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene of C₂₂ H₁₈ N₂ O₄.

FIG. 1 shows an infrared spectrum of1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene, taken by use of a KBrtablet, which indicates an absorption at 1005 cm⁻¹ characteristic ofdeformation vibration of trans-olefine, and absorptions characteristicof NH stretching vibration at 1510 cm⁻¹ and 1335 cm⁻¹.

Visible absorption spectrum (THF) λmax 448 nm

[Preparation of 1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene]

59.2 g of the previously obtained1,10-bis(4-nitrophenyl)-1,3,5,7,9-decapentaene was added to 1,600 ml ofdimethylformamide. With stirring, 118.4 g of iron powder and 54 ml of a6N solution of hydrochloric acid were then added to the above solution.The mixture was further stirred at 90° C. to 99° C. for 3 hours, andthen cooled to 80° C. The mixture was then adjusted to pH 9.0 by using a50% aqueous solution of sodium hydroxide. Then, insoluble components,together with Celite, were removed from the mixture by filtration. Thefiltrate was diluted with 600 ml of water and allowed to stand at roomtemperature. The resulting crystals were filtered off, washed withwater, and dried, so that 45.7 g of brown-red crystals in the form offlat plates were obtained in a 92% yield.

The thus obtained crystals were recrystallized from a mixed solvent ofdimethylformamide and water, whereby1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene was obtained in the formof dark red plates. The melting point, corresponding to an exothermicpeak temperature of the product in a thermal analysis (DSC), was 262° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 84.02        7.07   8.91                                           Found      83.79        7.13   8.99                                           ______________________________________                                    

The above calculation was based on the formula for1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene of C₂₂ H₂₂ N₂.

FIG. 2 shows an infrared spectrum of1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene, taken by use of a KBrtablet, which indicates an absorption between 3500 cm⁻¹ and 3200 cm⁻¹characteristic of stretching vibration of primary amine, and anabsorption characteristic of trans-olefine out-of-plane deformationvibration at 1010 cm⁻¹.

[Preparation of Bis(diazonium)salt]

30.0 g of the previously obtained1,10-bis(4-aminophenyl)-1,3,5,7,9-decapentaene was added to 425 ml of a15 vol. %-aqueous solution of sulfuric acid, and the mixture was stirredat 50° C. for 90 minutes. After the mixture was rapidly cooled to -5°C., an aqueous solution consisting of 14.46 g of sodium nitrite and 45ml of water was added dropwise to the above mixture over a period of 90minutes, with the temperature maintained at -5° C. to -3° C. Thisreaction mixture was stirred at -5° C. for 30 minutes and the resultingproduct was separated from the reaction mixture by filtration. Thisproduct was dissolved in 10 ml of cold water and a small amount ofinsoluble components in the above-prepared aqueous solution, was removedtogether with Celite by filtration. To the thus obtained filtrate, a42%-aqueous solution of borofluoric acid was added, and then theprecipitated crystals were separated from the solution by filtration anddried, so that 42.1 g of a dark red bis(diazonium)salt was obtained inan 86.0% yield. The decomposing point of the product was 120° C.

FIG. 3 shows an infrared spectrum of this bis(diazonium)salt, taken byuse of a KBr tablet, which indicates an absorption at 2230 cm⁻¹characteristic of stretching vibration of diazonium salt, and anabsorption characteristic of trans-olefine out-of-plane deformationvibration at 1010 cm⁻¹.

[Preparation of Bisazo Pigment]

0.26 g of the previously obtained bis(diazonium)salt was added to asolution consisting of 50 ml of dimethylformamide and 0.19 g ofacetoacetanilide. Further, to this mixture, 2 ml of 8.6%-aqueoussolution of sodium acetate was added dropwise at room temperature. Afterthe dropwise addition of the aqueous solution of sodium acetate, themixture was stirred for 3 hours at room temperature and diluted with 40ml of water. The resulting precipitate was separated from the solutionby filtration, washed with water and dried, so that 0.30 g of a powderydark red product was obtained in an 87% yield. This product wasrecrystallized from dimethylformamide, whereby a dark red bisazo pigmentNo. 176 of the following formula listed in Table 1 was obtained in theform of needles. ##STR265##

Exothermic peak temperature (DSC): 252° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 73.01        5.56   12.17                                          Found      72.80        5.38   12.02                                          ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₄₂ H₃₈ N₆ O₄.

FIG. 4 shows an infrared spectrum of the bisazo pigment No. 176, takenby use Of a KBr tablet, which indicates an absorption characteristic oftrans-olefine out-of-plane deformation vibration at 1000 cm⁻¹.

Synthesis Example 2

0.51 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 100 ml ofdimethylformamide and 0.48 g of N-methyl-3-hydroxynaphthalimide.Further, to this mixture, 4 ml of an 8.6%-aqueous solution of sodiumacetate was added dropwise at room temperature. After the addition ofthe aqueous solution of sodium acetate, the mixture was stirred for 3hours at room temperature. The resulting precipitate was separated fromthe solution by filtration, washed with 200 ml of dimethylformamide fivetimes and further with water twice, and dried, so that 0.65 g of powderyblue-black bisazo pigment No. 115 of the following formula listed inTable 1 was obtained in an 82% yield. ##STR266##

Exothermic peak temperature (DSC): 254° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 72.89        4.34   10.63                                          Found      72.61        4.35   10.45                                          ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₄₈ H₃₄ N₆ O₆.

FIG. 5 shows an infrared spectrum of the bisazo pigment No. 115, takenby use of a KBr tablet, indicated an absorption characteristic oftrans-olefine out-of-plane deformation vibration at 1005 cm⁻¹.

Synthesis Example 3

0.26 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 50 ml ofdimethyl-formamide and 0.21 g of 3-hydroxy-2-naphthoic acid methylester. Further, to this mixture, 2 ml of an 8.6%-aqueous solution ofsodium acetate was added dropwise at room temperature. After thedropwise addition of the aqueous solution of sodium acetate, the mixturewas stirred for 3 hours at room temperature and diluted with 20 ml ofwater. The resulting precipitate was separated from the solution byfiltration, washed with water and dried, so that 0.37 g of a blue-blackproduct in the form of powder was obtained substantially in a yield of100%. This product was recrystallized from nitrobenzene, whereby abluish black bisazo pigment No. 178 of the following formula listed inTable 1 was obtained in the form of needles. ##STR267##

Exothermic peak temperature: 280° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 74.59        4.91   7.56                                           Found      74.40        4.73   7.38                                           ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₄₆ H₃₆ N₄ O₆.

FIG. 6 shows an infrared spectrum of the bisazo pigment No. 178, takenby use of a KBr tablet, which indicates an absorption characteristic ofthe carbonyl stretching vibration at 1700 cm⁻¹ and an absorptioncharacteristic of trans-olefine out-of-plane deformation vibration at1005 cm⁻¹.

Synthesis Example 4

0.26 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 50 ml ofdimethylformamide and 0.23 g of 3-hydroxy-2-N,N-dimethyl naphthoic acidamide. Further, to this mixture, 2 ml of an 8.6%-aqueous solution ofsodium acetate was added dropwise at room temperature. After thedropwise addition of the aqueous solution of sodium acetate, the mixturewas stirred for 3 hours at room temperature and diluted with a 50 vol. %aqueous solution of methanol. The resulting precipitate was separatedfrom the solution by filtration, washed with water and dried, so that0.38 g of a bluish black product in the form of powder was obtainedsubstantially in a yield of 100%. This product was recrystallized fromnitrobenzene, whereby a bluish black bisazo pigment No. 177 of thefollowing formula listed in Table 1 was obtained in the form of needles.##STR268##

Exothermic peak temperature: 288° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 75.16        5.53   10.96                                          Found      74.72        5.27   10.69                                          ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₄₈ H₄₂ N₆ O₄.

FIG. 7 shows an infrared spectrum of the bisazo pigment No. 177, takenby use of a KBr tablet, which indicates an absorption characteristic ofthe carbonyl stretching vibration at 1640 cm⁻¹ and an absorptioncharacteristic of trans-olefine out-of-plane deformation vibration at1010 cm⁻¹.

Synthesis Example 5

0.51 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 100 ml ofdimethylformamide and 0.55 g of 3-hydroxy-2-naphthoic acid anilide. Tothis mixture, 4 ml of an 8.6%-aqueous solution of sodium acetate wasadded dropwise at room temperature. After the addition of the aqueoussolution of sodium acetate, the mixture was stirred for 3 hours at roomtemperature. The resulting precipitate was separated from the solutionby filtration, washed with 200 ml of dimethylformamide five times andfurther with water twice, and dried, so that 0.77 g of a powdery bluishblack bisazo pigment No. 1 of the following formula listed in Table 1was obtained in an 89% yield. ##STR269##

Exothermic peak temperature: 288° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 77.93        4.92   9.74                                           Found      78.00        4.97   9.65                                           ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₅₆ H₄₂ N₆ O₄.

Visible spectrum in a DMF solution of 10 vol. % of ethylene diamine:λmax. 596 nm

FIG. 8 shows an infrared spectrum of the bisazo pigment No. 1, taken byuse of a KBr tablet, indicated an absorption characteristic ofstretching vibration between C and 0 in secondary amido at 1675 cm⁻¹ andabsorptions characteristic of trans-olefine out-of-plane deformationvibration at 1020 cm⁻¹ and 1000 cm⁻¹.

Synthesis Example 6

0.51 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 100 ml ofdimethylformamide and 0.74 g of2-hydroxy-3-phenylcarbamoyl-11H-benzo[a]carbazole. Further, to thismixture, 4 ml of an 8.6%-aqueous solution of sodium acetate was addeddropwise at room temperature. After the addition of the aqueous solutionof sodium acetate, the mixture was stirred for 3 hours at roomtemperature. The resulting precipitate was separated from the solutionby filtration, washed with dimethylformamide seven times and with watertwice, and dried, so that 0.96 g of a powdery bluish black bisazopigment No. 58 of the following formula listed in Table 1 was obtainedin a 92% yield. ##STR270##

Exothermic peak temperature: 283° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 78.43        4.66   10.76                                          Found      78.66        4.62   10.49                                          ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₆₈ H₄₈ N₈ O₄.

Visible spectrum in a DMF solution of 10 vol. % of ethylene diamine:λmax. 621 nm

FIG. 9 shows an infrared spectrum of the bisazo pigment No. 58, taken byuse of a KBr tablet, which indicates an absorption characteristic ofstretching vibration between C and O in secondary amido at 1670 cm⁻¹ andan absorption characteristic of trans-olefine out-of-plane deformationvibration at 1005 cm⁻¹.

Synthesis Examples 7 to 32

Synthesis Example 6 was repeated except that the coupler (ArH) employedin Synthesis Example 6 was replaced by the respective couplers shown inthe following Table 2, whereby the bisazo pigments were obtained asshown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________     ##STR271##                                                                    ##STR272##                                                                         ##STR273##                                                                                  ##STR274##                                                                                ##STR275##                                                                           ##STR276##                                                                               ##STR277##                  __________________________________________________________________________    7 (163)                                                                             ##STR278##                                                                                  ##STR279## 269     79.75 4.59 8.64 (79.80) (4.82)                                               (8.73)     1675 1020                    8 (8)                                                                               ##STR280##                                                                                  ##STR281## 271     75.20 5.20 9.08 (75.46) (5.03)                                               (9.11)                                                                                    ##STR282##                                                                       ##STR283##                                                                      ##STR284##             9 (10)                                                                              ##STR285##                                                                                  ##STR286## 278     75.53 4.88 9.07 (75.46) (5.03)                                               (9.11)                                                                                    ##STR287##                                                                       ##STR288##                                                                      ##STR289##             10 (4)                                                                              ##STR290##                                                                                  ##STR291## 227     77.69 5.05 9.03 (78.18) (5.21)                                               (9.43)                                                                                    ##STR292##                                                                       ##STR293##                                                                      ##STR294##             11 (16)                                                                             ##STR295##                                                                                  ##STR296## 276     71.79 4.16 8.90 (72.18) (4.33)                                               (9.02)                                                                                    ##STR297##                                                                       ##STR298##                                                                      ##STR299##             12 (34)                                                                             ##STR300##                                                                                  ##STR301## 301     70.26 4.02 11.46 (70.58) (4.23)                                              (11.76)                                                                                   ##STR302##                                                                       ##STR303##                                                                      ##STR304##             13 (37)                                                                             ##STR305##                                                                                  ##STR306## 252     75.53 5.29 11.52 (75.93) (5.52)                                              (11.81)                                                                                   ##STR307##                                                                       ##STR308##                                                                      ##STR309##             14 (64)                                                                             ##STR310##                                                                                  ##STR311## 293     76.03 4.53 9.89 (76.34) (4.77)                                               (10.18)    1670 1000                    15 (65)                                                                             ##STR312##                                                                                  ##STR313## 286     76.30 4.60 9.73 (76.34) (4.77)                                               (10.18)    1670 1000                    16 (66)                                                                             ##STR314##                                                                                  ##STR315## 299     76.19 4.62 9.63 (76.34) (4.77)                                               (10.18)    1670 1000                    17 (59)                                                                             ##STR316##                                                                                  ##STR317## 287     78.28 4.68 10.14 (78.62) (4.91)                                              (10.48)    1675 1000                    18 (60)                                                                             ##STR318##                                                                                  ##STR319## 275     78.25 4.74 9.95 (78.62) (4.91)                                               (10.48)    1670 1000                    19 (61)                                                                             ##STR320##                                                                                  ##STR321## 289     77.94 4.67 10.03 (78.62) (4.91)                                              (10.48)    1670 1000                    20 (70)                                                                             ##STR322##                                                                                  ##STR323## 295     72.93 4.00 9.82 (73.57) (4.19)                                               (10.10)    1675 1000                    21 (71)                                                                             ##STR324##                                                                                  ##STR325## 283     73.21 4.15 9.90 (73.57) (4.19)                                               (10.10)    1680 1000                    22 (72)                                                                             ##STR326##                                                                                  ##STR327## 286     73.47 4.25 9.81 (73.57) (4.19)                                               (10.10)    1680 1005                    23 (73)                                                                             ##STR328##                                                                                  ##STR329## 298     71.88 3.92 11.99 (72.19) (4.11)                                              (12.38)    1675 1000                    24 (74)                                                                             ##STR330##                                                                                  ##STR331## 288     71.84 3.90 11.93 (72.19) (4.11)                                              (12.38)    1670 1000                    25 (75)                                                                             ##STR332##                                                                                  ##STR333## 300     71.90 3.97 12.02 (72.19) (4.11)                                              (12.38)    1680 1000                    26 (62)                                                                             ##STR334##                                                                                  ##STR335## 275     78.84 5.00 9.76 (78.80) (5.15)                                               (10.21)    1670 1000                    27 (63)                                                                             ##STR336##                                                                                  ##STR337## 342     78.48 4.92 9.78 (78.80) (5.15)                                               (10.21)    1670 1000                    28 (67)                                                                             ##STR338##                                                                                  ##STR339## 294     76.14 4.79 9.69 (76.57) (5.01)                                               (9.92)     1670 995                     29 (69)                                                                             ##STR340##                                                                                  ##STR341## 283     76.55 4.84 9.42 (76.57) (5.01)                                               (9.92)     1660 995                     30 (212)                                                                            ##STR342##                                                                                  ##STR343## 307     78.40 5.00 9.96 (78.80) (5.16)                                               (10.21)    1670 1000                    31 (211)                                                                            ##STR344##                                                                                  ##STR345## 309     73.14 3.83 9.82 (73.57) (4.19)                                               (10.10)    1670 995                     32 (213)                                                                            ##STR346##                                                                                  ##STR347## 302     75.94 4.56 9.68 (76.34) (4.77)                                               (10.18)    1670 1000                    __________________________________________________________________________     *Numbers in the parentheses in the column of Synthesis Examples indicate      bisazo pigment No. in Table 2.                                           

Synthesis Example 33

0.51 g of the same bis(diazonium)salt as that employed in SynthesisExample 1 was added to a solution consisting of 100 ml ofdimethylformamide and 0.61 g of 3-hydroxy-2-naphthoic acidbenzylidenehydrazide. To this mixture, 4 ml of an 8.6%-aqueous solutionof sodium acetate was added dropwise at room temperature. After theaddition of the aqueous solution of sodium acetate, the mixture wasstirred for 3 hours at room temperature. The resulting precipitate wasseparated from the solution by filtration, washed with 200 ml ofdimethylformamide six times and further with water twice, and dried, sothat 0.85 g of a powdery bluish black bisazo pigment No. 77 of thefollowing formula listed in Table 1 was obtained in a 93% yield.##STR348##

Exothermic peak temperature: 263° C.

The results of the elemental analysis of the thus obtained product wereas follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 75.95        4.85   12.22                                          Found      75.75        4.52   12.12                                          ______________________________________                                    

The above calculation was based on the formula for the bisazo pigment ofC₅₈ H₄₄ N₈ O₄.

FIG. 10 shows an infrared spectrum of the bisazo pigment No. 77, takenby use of a KBr tablet, which indicates an absorption characteristic ofCO stretching vibration at 1670 cm⁻¹ and an absorption characteristic oftrans-olefine out-of-plane deformation vibration at 1005 cm⁻¹.

Synthesis Examples 34 to 41

Synthesis Example 33 was repeated except that the coupler (ArH) employedin Synthesis Example 33 was replaced by the respective couplers shown inthe following Table 3, whereby the bisazo pigments were obtained asshown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________     ##STR349##                                                                    ##STR350##                                                                         ##STR351##                                                                                  ##STR352##                                                                                ##STR353##                                                                           ##STR354##                                                                               ##STR355##                  __________________________________________________________________________    34 (167)                                                                            ##STR356##                                                                                  ##STR357## 277     73.42 4.60 11.76 (73.43) (4.68)                                              (11.81)    1680 1005                    35 (90)                                                                             ##STR358##                                                                                  ##STR359## 293     76.21 4.40 12.54 (76.76) (4.61)                                              (12.79)    1670 1005                    36 (172)                                                                            ##STR360##                                                                                  ##STR361## 300     74.55 4.76 12.01 (74.58) (4.48)                                              (12.43)    1670 1000                    37 (174)                                                                            ##STR362##                                                                                  ##STR363## 298     72.51 4.42 11.60 (72.83) (4.59)                                              (11.80)    1670 1000                    38 (173)                                                                            ##STR364##                                                                                  ##STR365## 356     66.93 3.94 13.07 (67.04) (4.08)                                              (13.48)    1670 1000                    39 (175)                                                                            ##STR366##                                                                                  ##STR367## 298     76.04 4.39 11.11 (76.32) (4.44)                                              (11.41)    1670 1000                    40 (179)                                                                            ##STR368##                                                                                  ##STR369## 290     77.81 4.30 11.36 (78.36) (4.56)                                              (11.72)    1665 1000                    41 (180)                                                                            ##STR370##                                                                                  ##STR371## 284     79.40 4.25 10.45 (79.72) (4.52)                                              (10.81)    1665 1000                    __________________________________________________________________________

Synthesis Examples 42 to 77

Synthesis Example 33 was repeated except that the coupler (ArH )employed in Synthesis Example 33 was replaced by the respective couplersshown in the following Table 4, whereby bisazo pigments as shown inTable 4 were obtained.

                                      TABLE 4                                     __________________________________________________________________________     ##STR372##                                                                    ##STR373##                                                                        ##STR374##                                                                                     ##STR375##                                                                                         ##STR376##                                                                        ##STR377##                                                                              ##STR378##           __________________________________________________________________________    42 (2)                                                                             ##STR379##                                                                                     ##STR380##          270  77.85 5.01 9.11 (78.17)                                                      (5.21) (9.43)                                                                           1680                                                                              1000              43 (33)                                                                            ##STR381##                                                                                     ##STR382##          269  70.00 4.20 11.50 (70.58)                                                     (4.23) (11.76)                                                                          1680                                                                              1000              44 (44)                                                                            ##STR383##                                                                                     ##STR384##          267  77.63 5.02 8.79 (78.40)                                                      (5.49) (9.15)                                                                           1670                                                                              1000              45 (181)                                                                           ##STR385##                                                                                     ##STR386##          265  71.90 3.83 8.97 (71.93)                                                      (4.10) (8.99)                                                                           1680                                                                              1000              46 (42)                                                                            ##STR387##                                                                                     ##STR388##          257  71.89 4.24 8.97 (72.55)                                                      (4.63) (8.76)                                                                           1680                                                                              1000              47 (50)                                                                            ##STR389##                                                                                     ##STR390##          274  71.92 4.30 8.20 (72.92)                                                      (4.91) (8.51)                                                                           1670                                                                              1000              48 (182)                                                                           ##STR391##                                                                                     ##STR392##          292  71.44 3.66 10.97 (71.98)                                                     (4.04) (11.20)                                                                          1680                                                                              1000              49 (183)                                                                           ##STR393##                                                                                     ##STR394##          284  70.98 3.82 10.91 (71.98)                                                     (4.04) (11.20)                                                                          1680                                                                              1005              50 (185)                                                                           ##STR395##                                                                                     ##STR396##          306  70.22 4.26 13.85 (71.44)                                                     (4.35) (14.37)                                                                          unclear                                                                           1015              51 (187)                                                                           ##STR397##                                                                                     ##STR398##          302  68.82 4.46 13.35 (69.16)                                                     (4.21) (13.91)                                                                          1660                                                                              1005              52 (191)                                                                           ##STR399##                                                                                     ##STR400##          303  70.79 4.15 13.81 (71.44)                                                     (4.35) (14.37)                                                                          1680                                                                              1005              53 (186)                                                                           ##STR401##                                                                                     ##STR402##          311  69.32 4.07 12.98 (69.89)                                                     (4.11) (13.59)                                                                          unclear                                                                           1005              54 (106)                                                                           ##STR403##                                                                                     ##STR404##          289  75.62 4.26 7.57 (76.20)                                                      (4.58) (7.62)                                                                           1670                                                                              1005              55 (188)                                                                           ##STR405##                                                                                     ##STR406##          297  77.42 4.99 10.39 (78.13)                                                     (5.02) (10.72)                                                                          1665                                                                              1005              56 (192)                                                                           ##STR407##                                                                                     ##STR408##          303  71.82 3.89 11.84 (72.77)                                                     (4.02) (12.13)                                                                          1685                                                                              1000              57 (164)                                                                           ##STR409##                                                                                     ##STR410##          289  77.98 4.24 7.83 (78.29)                                                      (4.45) (8.06)                                                                           1670                                                                              1000              58 (189)                                                                           ##STR411##                                                                                     ##STR412##          293  79.22 4.62 9.50 (79.69)                                                      (4.94) (9.79)                                                                           1665                                                                              1010              59 (190)                                                                           ##STR413##                                                                                     ##STR414##          307  77.95 4.79 11.01 (78.53)                                                     (4.79) (11.45)                                                                          1660                                                                              1000              60 (193)                                                                           ##STR415##                                                                                     ##STR416##          301  76.60 4.62 12.30 (77.68)                                                     (4.86) (12.64)                                                                          1670                                                                              1000              61 (194)                                                                           ##STR417##                                                                                     ##STR418##          284  80.01 4.05 9.68 (79.97)                                                      (4.60) (9.82)                                                                           1670                                                                              1000              62 (195)                                                                           ##STR419##                                                                                     ##STR420##          311  79.89 4.25 9.66 (79.97)                                                      (4.60) (9.82)                                                                           1670                                                                              1000              63 (196)                                                                           ##STR421##                                                                                     ##STR422##          290  76.92 4.08 10.77 (76.97)                                                     (4.58) (10.95)                                                                          1660.sup.a)                                                                   (broad)                                                                           1000              64 (197)                                                                           ##STR423##                                                                                     ##STR424##          319  72.01 3.92 9.12 (71.84)                                                      (4.32) (9.58)                                                                           1670                                                                              1000              65 (198)                                                                           ##STR425##                                                                                     ##STR426##          305  72.45 3.92 9.53 (71.84)                                                      (4.32) (9.58)                                                                           1670                                                                              1000              66 (199)                                                                           ##STR427##                                                                                     ##STR428##          309  72.06 3.84 9.38 (71.84)                                                      (4.32) (9.58)                                                                           1670                                                                              1005              67 (200)                                                                           ##STR429##                                                                                     ##STR430##          318  73.70 4.04 9.87 (73.86)                                                      (4.44) (9.85)                                                                           1675                                                                              1000              68 (201)                                                                           ##STR431##                                                                                     ##STR432##          320  73.65 4.10 9.75 (73.86)                                                      (4.44) (9.85)                                                                           1675                                                                              1005              69 (202)                                                                           ##STR433##                                                                                     ##STR434##          310  68.44 3.29 9.32 (69.27)                                                      (3.77) (9.51)                                                                           1675                                                                              1005              70 (203)                                                                           ##STR435##                                                                                     ##STR436##          335  68.69 3.35 9.36 (69.27)                                                      (3.77) (9.51)                                                                           1675                                                                              1005              71 (204)                                                                           ##STR437##                                                                                     ##STR438##          322  67.88 3.40 11.18 (68.05)                                                     (3.70) (11.67)                                                                          1675                                                                              1000              72 (205)                                                                           ##STR439##                                                                                     ##STR440##          329  67.15 3.48 11.29 (68.05)                                                     (3.70) (11.67)                                                                          1680                                                                              1000              73 (206)                                                                           ##STR441##                                                                                     ##STR442##          382  67.94 3.43 11.37 (68.05)                                                     (3.70) (11.67)                                                                          1680                                                                              1005              74 (207)                                                                           ##STR443##                                                                                     ##STR444##          297  73.55 4.33 9.40 (74.15)                                                      (4.68) (9.61)                                                                           1675                                                                              1000              75 (208)                                                                           ##STR445##                                                                                     ##STR446##          330  68.38 3.89 8.78 (69.65)                                                      (4.02) (9.29)                                                                           1680                                                                              1010              76 (209)                                                                           ##STR447##                                                                                     ##STR448##          304  73.48 4.38 9.39 (74.15)                                                      (4.68) (9.61)                                                                           1670                                                                              1000              77 (210)                                                                           ##STR449##                                                                                     ##STR450##          319  72.76 4.01 11.79 (72.21)                                                     (4.16) (12.03)                                                                          1675                                                                              1005              __________________________________________________________________________

In the electrophotographic photoconductor according to the presentinvention, the bisazo pigment having the general formula (I) iscontained in a photoconductive layer as a charge generating material.The bisazo pigments can be employed in different ways, for example, asshown in FIG. 11 and FIG. 12.

In the photoconductor as shown in FIG. 11, there is formed on anelectroconductive support 11 a two-layered photoconductive layer 191comprising a charge generation layer 15 consisting essentially of abisazo pigment 13 serving as a charge generating material and a chargetransport layer 17 containing a charge transporting material.

In this photoconductor, light which has passed through the chargetransport layer 17 reaches the charge generation layer 15. The chargecarriers which are necessary for the light decay for latentelectrostatic image formation are generated by the bisazo pigment 13contained in the charge generation layer 15, accepted and transported bythe charge transport layer 17.

In the photoconductor as shown in FIG. 12, there is formed on anelectroconductive support 11 a photoconductive layer 192 mainlycomprising a bisazo pigment 13, a charge transporting material and aninsulating binder agent. In this photoconductor, the bisazo pigment 13functions as a charge generating material.

Besides the photoconductors as shown in FIG. 11 and FIG. 12, aphotoconductor in which the overlaying order of the charge generationlayer 15 containing the bisazo pigment and the charge transport layer 17is reversed as compared with the electrophotographic photoconductor asshown in FIG. 11 can be employed.

In the photoconductor as shown in FIG. 11, it is preferable that thethickness of the charge generation layer 15 of the photoconductive layer191 be in the range of 0.01 to 5 μm, more preferably in the range of0.05 to 2 μm.

When the thickness of the charge generation layer 15 is 0.01 μm or less,the charge carriers generated are not sufficient for the light decay forlatent electrostatic image formation. When the thickness of the chargegeneration layer 15 is 5 μm or more, the residual electric potentialremains too high.

It is preferable that the thickness of the charge transport layer 17 bein the range of 3 to 50 μm, more preferably in the range of 5 to 20 μm.

When the thickness of the charge transport layer 17 is 3 μm or less, theelectrical charge quantity is not sufficient for practical use. When thethickness of the charge transport layer 17 is 50 μm or more, theresidual electric potential remains too high.

The charge generation layer 15 comprises the bisazo pigment of thegeneral formula (I), a binder agent and a plasticizer. It is preferablethat the amount of the bisazo pigment contained in the charge generationlayer 15 be 30 wt. % or more, more preferably 50 wt. % or more.

The charge transport layer 17 comprises the charge transportingmaterial, a binder agent and a plasticizer. It is preferable that theamount of the charge transporting material contained in the chargetransport layer 17 be in the range of 10 to 95 wt. %, more preferably inthe range of 30 to 90 wt. %. When the amount of the charge transportingmaterial contained in the charge transport layer 17 is less than 10 wt.%, the charge carriers are hardly transported. When the amount of thecharge transporting material contained in the charge transport layer 17is 95 wt. % or more, the mechanical strength of the film of thephotoconductor is considerably insufficient for practical use.

In the photoconductor as shown in FIG. 15, it is preferable that thethickness of the photoconductive layer 192 be in the range of 3 to 50μm, more preferably in the range of 5 to 20 μm.

It is preferable that the amount of the bisazo pigment contained in thephotoconductive layer 192 be 50 wt. % or less, more preferably 20 wt. %or less. It is preferable that the amount of the charge transportingmaterial contained in the photoconductive layer 192 be in the range of10 to 95 wt. %, more preferably in the range of 30 to 90 wt. %.

In the electrophotographic photoconductor according to the presentinvention, conventional materials can be employed for each elements suchas the electroconductive support and the charge transport material.

Specific examples of the electroconductive support for theelectrophotographic photoconductor according to the present inventioninclude a metallic plate made of aluminum, copper and zinc, a plasticsheet made of polyester, a plastic film on which a metal such asaluminum and tin dioxide is evaporated, and a sheet of paper which hasbeen treated so as to be electroconductive.

Specific examples of the binder agent for use in the present inventionare condensation resins such as polyamide, polyurethane, polyester,epoxy resin, polyketone, polycarbonate and polyacetal; and vinylpolymers such as polyvinylketone, polystyrene, poly-N-vinylcarbazole andpolyacrylamide. Besides the above-listed binder agents, otherconventional electrically insulating and adhesive resins can be used.

Specific examples of the plasticizer for use in the present inventionare halogenated paraffin, polybiphenyl chloride, dimethylnaphthalene anddibutyl phthalate. In addition, silicone oil can be added to thephotoconductor to improve the surface properties thereof.

As the charge transporting materials, there are positive holetransporting materials and electron transporting materials.

Specific examples of the positive hole transporting materials are thecompounds represented by the following general formulas (1) through(11): ##STR451## wherein R¹¹⁵ represents a methyl group, an ethyl group,a 2-hydroxyethyl group, or a 2-chloroethyl group; R¹²⁵ represents amethyl group, an ethyl group, a benzyl group or a phenyl group; R¹³⁵represents hydrogen, chlorine, bromine, an alkyl group having 1 to 4carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, adialkylamino group or a nitro group. ##STR452## wherein Ar³ representsan unsubstituted or substituted naphthalene ring, an unsubstituted orsubstituted anthracene ring, an unsubstituted or substituted styrylgroup, a pyrydine ring, a furan ring, or a thiophene ring; and R¹⁴⁵represents an alkyl group or a benzyl group. ##STR453## wherein R¹⁵⁵represents an alkyl group, a benzyl group, a phenyl group, or a naphthylgroup; R¹⁶⁵ represents hydrogen, an alkyl group having 1 to 3 carbonatoms, an alkoxyl group having 1 to 3 carbon atoms, a dialkylaminogroup, a diaralkylamino group or a diarylamino group; n is an integer of1 to 4, and when n is 2 or more, R¹⁶⁵ s may be the same or different;and R¹⁷⁵ represents hydrogen or a methoxy group. ##STR454## wherein R¹⁸⁵represents an alkyl group having 1 to 11 carbon atoms, an unsubstitutedor substituted phenyl group, or a heterocyclic ring; R¹⁹⁵ and R²⁰⁵ andmay be the same or different and each represent hydrogen, an alkyl grouphaving 1 to 4 carbon atoms, a hydroxylalkyl group, a chloroalkyl group,or an unsubstituted or substituted aralkyl group, R¹⁹⁵ and R²⁰⁵ may bebonded to each other to form a heterocyclic ring containing nitrogenatom(s); each R²¹⁵ may be the same or different and represents hydrogen,an alkyl group having 1 to 4 carbon atoms, an alkoxyl group or halogen.##STR455## wherein R²²⁵ represents hydrogen or halogen; and Ar⁴represents an unsubstituted or substituted phenyl group, anunsubstituted or substituted naphthyl group, an unsubstituted orsubstituted anthryl group or an unsubstituted or substituted carbazolylgroup. ##STR456## wherein R²³⁵ represents hydrogen, halogen, a cyanogroup, an alkoxyl group having 1 to 4 carbon atoms, or an alkyl grouphaving 1 to 4 carbon atoms; Ar⁵ represents ##STR457## wherein R²⁴⁵represents an alkyl group having 1 to 4 carbon atoms; R²⁵⁵ representshydrogen, halogen, an alkyl group having 1 to 4 carbon atoms, an alkoxylgroup having 1 to 4 carbon atoms, or a dialkylamino group; n is aninteger of 1 or 2, and when n is 2, each R²⁵⁵ may be the same ordifferent; and R²⁶⁵ and R²⁷⁵ each represent hydrogen, an unsubstitutedor substituted alkyl group having 1 to 4 carbon atoms, or anunsubstituted or substituted benzyl group. ##STR458## wherein R²⁸⁵ andR²⁹⁵ each represent a carbazolyl group, a pyridyl group, a thienylgroup, an indolyl group, a furyl group, an unsubstituted or substitutedphenyl group, an unsubstituted or substituted styryl group, anunsubstituted or substituted naphthyl group, an unsubstituted orsubstituted anthryl group, which may have a substituent selected fromthe group consisting of a dialkylamino group, an alkyl group, an alkoxylgroup, a carboxyl group or an ester thereof, halogen, a cyano group, anaralkylamino group, an N-alkyl-N-aralkylamino group, an amino group, anitro group and an acetylamino group. ##STR459## wherein R³⁰⁵ representsa lower alkyl group or a benzyl group; R³¹⁵ represents hydrogen, a loweralkyl group, a lower alkoxyl group, halogen, a nitro group, an aminogroup which may have as a substituent a lower alkyl group or a benzylgroup, and n is an integer of 1 or 2. ##STR460## wherein R³²⁵ representshydrogen, an alkyl group, an alkoxyl group or halogen; R³³⁵ and R³⁴⁵each represent an alkyl group, an unsubstituted or substituted aralkylgroup, or an unsubstituted or substituted aryl group; R³⁵⁵ representshydrogen or an unsubstituted or substituted phenyl group, and Ar⁶represents a phenyl group or a naphthyl group. ##STR461## wherein n isan integer of 0 or 1; R³⁶⁵ represents hydrogen, an alkyl group, or anunsubstituted or substituted phenyl group; A¹ represents ##STR462## a9-anthryl group or an unsubstituted or substituted N-alkylcarbazolylgroup, wherein R³⁷⁵ represents hydrogen, an alkyl group, an alkoxylgroup, halogen, or ##STR463## wherein R³⁸⁵ and R³⁹⁵ each represent analkyl group, or an unsubstituted or substituted aryl group, and R³⁸⁵ andR³⁹⁵ may form a ring in combination; m is an integer of 0, 1, 2, or 3,and when m is 2 or more, each R³⁷⁵ may be the same or different.##STR464## wherein R⁴⁰⁵, R⁴¹⁵ and R⁴²⁵ each represent hydrogen, a loweralkyl group, a lower alkoxyl group, a dialkylamino group, or halogen;and n is an integer of 0 or 1.

Specific examples of the compound represented by the above generalformula (1) are 9-ethylcarbazole-3-aldehyde, 1-methyl-1-phenylhydrazone,9-ethylcarbazole-3-aldehyde 1-benzyl-1-phenylhydrazone, and9-ethylcarbazole-3-aldehyde 1,1-diphenylhydrazone.

Specific examples of the compound represented by the above generalformula (2) are 4-diethylaminostylene-β-aldehyde1-methyl-1-phenylhydrazone, and 4-methoxynaphthalene-1-aldehyde1-benzyl-1-phenylhydrazone.

Specific examples of the compound represented by the above generalformula (3) are 4-methoxybenzaldehyde 1-methyl-1-phenylhydrazone,2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone,4-diethylaminobenzaldehyde 1,1-diphenyl-hydrazone, 4-methoxybenzaldehyde1-benzyl-1-(methoxy)phenylhydrazone, 4-diphenylaminobenzaldehyde1-benzyl-1-phenylhydrazone, and4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone.

Specific examples of the compound represented by the above generalformula (4) are 1,1-bis(4-dibenzylaminophenyl)propane,tris(4-diethylaminophenyl)methane,1,1-bis(4-dibenzylaminophenyl)propane, and2,2'-dimethyl-4,4'-bis(diethylamino)-triphenylmethane.

Specific examples of the compound represented by the above generalformula (5) are 9-(4-diethylaminostyryl) anthracene, and9-bromo-10-(4-diethylaminostyryl) anthracene.

Specific examples of the compound represented by the above generalformula (6) are 9-(4-dimethylaminobenzylidene) fluorene, and3-(9-fluorenylidene)-9-ethylcarbazole.

Specific examples of the compound represented by the above generalformula (7) are 1,2-bis(4-diethylaminostyryl) benzene, and1,2-bis(2,4-dimethoxystyryl)benzene.

Specific examples of the compound represented by the above generalformula (8) are 3-styryl-9-ethylcarbazole, and3-(4-methoxystyryl)-9-ethylcarbazole.

Specific examples of the compound represented by the above generalformula (9) are 4-diphenylaminostilbene, 4-dibenzylaminostilbene,4-ditolylaminostilbene, 1-(4-diphenylaminostyryl)naphthalene, and1-(4-diethylaminostyryl) naphthalene.

Specific examples of the compound represented by the above generalformula (10) are 4'-diphenylamino-α-phenylstilbene, and4'-methylphenylamino-α-phenylstilbene.

Specific examples of the compound represented by the above generalformula (11) are1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl) pyrazoline,and 1-phenyl-3-(4-dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline.

As other positive hole transporting materials, there are, for example,oxadiazole compounds such as2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole,2,5-bis[4-(4-diethylaminostyryl)phenyl]-1,3,4-oxadiazole, and2-(9-ethylcarbazolyl-3-)-5-(4-diethylaminophenyl)-1,3,4-oxadiazole; andoxazole compounds such as2-vinyl-4-(2-chlorophenyl)-5-(4-diethylaminophenyl)oxazole, and2-(4-diethylaminophenyl)-4-phenyloxazole. In addition, besides the abovelow-molecular weight compounds, the following polymeric compounds suchas poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinyl anthracene, pyrene-formaldehyde resin, andethylcarbazole-formaldehyde resin can be employed.

As electron transporting materials, there are, for example, chloranil,bromanil, tetracyanoethylene, tetracyanoquinone dimethane,2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone,2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone,2,6,8-trinitro-4H-indeno [1,2-b]thiophene-4-one, and1,3,7-trinitrodibenzothiophene-5,5-dioxide. These electron transportingmaterials can be employed alone or in combination.

In the electrophotographic photoconductor according to the presentinvention, an adhesive layer or a barrier layer may be interposedbetween the electroconductive support and the photoconductive layer whennecessary. The materials suitable for preparing the adhesive layer orbarrier layer are polyamide, nitrocellulose and aluminum oxide. It ispreferable that the thickness of the adhesive layer or barrier layer be1 μm or less.

The electrophotographic photoconductor as shown in FIG. 11 can beprepared by depositing a bisazo pigment on an electroconductive supportby vacuum deposition method as described in U.S. Pat. No. 3,973,959 andU.S. Pat. No. 3,996,049, or by coating on the electroconductive supporta dispersion of finely-divided particles of the bisazo pigment dispersedin an appropriate solvent, with a binder agent dissolved therein whennecessary, and drying the coated dispersion, and when necessary,subjecting the surface of the coated layer to buffing as disclosed inJapanese Laid-Open Patent Application 51-90827, or with the thickness ofthe coated layer adjusted appropriately. Finally, a solution of a chargetransporting material and a binder agent is coated on the coated layerand drying the coated solution.

The electrophotographic photoconductor as shown in FIG. 12 can beprepared by dispersing finely-divided particles of the bisazo pigment ina solution in which a charge transporting material and a binder agentare dissolved to form a dispersion, coating the dispersion on anelectroconductive support, and drying the coated dispersion.

In any of the electrophotographic photoconductors according to thepresent invention, it is preferable that the particle of the bisazopigment are pulverized with a ball mill to 5 μm or less, more preferably2 μm or less, when used. The coating of such bisazo pigments can beperformed by the conventional means, such as a doctor blade and wirebar, or by the conventional dipping method.

Copying by use of the electrophotographic photoconductor according tothe present invention can be performed by a process comprising the stepsof uniformly charging the surface of the photoconductive layer to apredetermined potential in the dark, exposing the uniformly chargedphotoconductive layer to a light image to form a latent electrostaticimage on the photoconductive layer, and developing the latentelectrostatic image with a developer to a visible image, and whennecessary by transferring the developed visible image to a transfersheet such a sheet of paper, and by fixing the transferred image to thetransfer sheet.

In the electrophotographic photoconductor according to the presentinvention, a bisazo pigment having 1,10-diphenyl-1,3,5,7,9-decapentaeneskeleton is used as a charge generating material. This photoconductorhas advantages that it has high photosensitivity and uniform spectralabsorbance not only in the entire visible region, but also in thesemiconductor laser wavelength region, and it can be manufactured easilyas compared with conventional photoconductors. Furthermore, thecharacteristics of this photoconductor can be maintained in the courseof repeated practical use.

Examples of the electrophotographic photoconductors according to thepresent-invention-will now be explained in detail, which are given forillustration of the present invention and are not intended to belimiting thereof.

EXAMPLE 1

7.5 parts by weight of a bisazo pigment No. 58 and 500 parts by weightof a tetrahydrofuran solution of a polyester resin (Trademark "Vylon200" made by Toyobo Company, Ltd.) with the amount of the solidcomponents contained therein being 0.5% were dispersed and ground in aball mill. The thus prepared dispersion was coated on an aluminumsurface of an aluminum-deposited polyester film by a doctor blade, anddried at room temperature, so that a charge generation layer having athickness of about 1 μm was formed on the aluminum-deposited polyesterfilm.

Furthermore, 2 parts by weight of9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone serving as acharge transporting material, 2 parts by weight of a polycarbonate resin(Trademark "Panlite K-1300" made by Teijin Limited.) and 16 parts byweight of tetrahydrofuran were mixed to form a solution. This solutionwas coated on the above formed charge generation layer by a doctor bladeand then dried at 80° C. for 2 minutes, and then at 105° C. for 5minutes, so that a charge transport layer having a thickness of about 20μm was formed on the charge generation layer. Thus a two-layered typeelectrophotographic photoconductor No. 1 according to the presentinvention as shown in FIG. 11 was prepared.

EXAMPLES 2 to 45

Example 1 was repeated except that the bisazo pigment No. 58 employed inExample 1 was replaced by the bisazo pigments listed in the followingTable 5, whereby electrophotographic photoconductors No. 2 to No. 45according to the present invention were prepared.

EXAMPLES 46 to 71

Example 1 was repeated except that9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone employed as acharge transport material in Example 1 was replaced by1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline,and the bisazo pigment No. 58 employed in Example 1 was replaced by thebisazo pigments listed in the following Table 6, wherebyelectrophotographic photoconductors No. 46 to No. 71 according to thepresent invention were prepared.

EXAMPLES 72 to 108

Example 1 was repeated except that9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone employed as acharge transport material in Example 1 was replaced byα-phenyl-4'-N,N-diphenylaminostilbene, and the bisazo pigment No. 58employed in Example 1 was replaced by the bisazo pigments listed in thefollowing Table 7, whereby electrophotographic photoconductors No. 72 toNo. 108 according to the present invention were prepared.

EXAMPLES 109 to 144

Example 1 was repeated except that9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone employed as acharge transport material in Example 1 was replaced by1,1-bis(4-dibenzylaminophenyl)propane, and the bisazo pigment No. 58employed in Example 1 was replaced by the bisazo pigments listed in thefollowing Table 8, whereby electrophotographic photoconductors No. 109to No. 144 according to the present invention were prepared.

With each of the electrophotographic photoconductors No. 1 through No.144 according to the present invention, the surface of thephotoconductive layer was charged negatively in the dark underapplication of -6 KV of corona charge for 20 seconds by a commerciallyavailable electrostatic copying sheet testing apparatus ("Paper AnalyzerSP 428" made by Kawaguchi Electro Works Co., Ltd.), and then allowed tostand in the dark for 20 seconds without applying any charge thereto,and the surface potential Vpo (V) of the photoconductor was measured.The photoconductor was then illuminated by a tungusten lamp in such amanner that the illuminance on the illuminated surface of thephotoconductor was 4.5 lux, and the exposure E_(1/2) (lux.sec) requiredto reduce the initial surface potential Vpo (V) to 1/2 the initialsurface potential Vpo (V) was measured. The results are given in Tables5 to 8.

                  TABLE 5                                                         ______________________________________                                        Photo-                                                                        Conductor Bisazo         Vpo    E1/2                                          No.       Pigment No.    (V)    (lux · sec)                          ______________________________________                                        1         58             700    4.24                                          2         90             676    2.13                                          3         163            572    7.91                                          4         8              715    2.67                                          5         34             376    3.77                                          6         65             780    4.76                                          7         66             860    5.62                                          8         59             500    4.68                                          9         60             772    3.78                                          10        61             812    4.37                                          11        71             576    1.77                                          12        72             506    1.13                                          13        62             431    1.63                                          14        67             591    1.55                                          15        69             645    4.45                                          16        179            650    1.98                                          17        180            723    1.44                                          18        172            572    1.39                                          19        174            377    1.31                                          20        173            499    1.78                                          21        175            320    1.26                                          22        115            130    4.19                                          23        181            408    7.93                                          24        50             278    4.59                                          25        183            294    3.73                                          26        187            540    7.49                                          27        186            196    8.45                                          28        106            240    4.30                                          29        189            436    13.68                                         30        193            560    4.11                                          31        194            346    1.70                                          32        195            422    1.93                                          33        196            863    1.71                                          34        198            766    2.72                                          35        199            529    1.66                                          36        200            122    0.62                                          37        201            291    0.91                                          38        202            596    2.43                                          39        204            646    8.64                                          40        207            191    0.78                                          41        209            426    0.88                                          42        210            233    1.09                                          43        211            300    1.19                                          44        212            298    2.05                                          45        213            731    3.60                                          ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Photo-                                                                        Conductor Bisazo         Vpo    E1/2                                          No.       Pigment No.    (V)    (lux · sec)                          ______________________________________                                        46        1              630    8.50                                          47        58             120    0.90                                          48        77             1060   7.21                                          49        90             200    0.79                                          50        163            420    3.52                                          51        10             1025   9.21                                          52        4              480    4.71                                          53        65             390    1.17                                          54        66             480    1.36                                          55        60             495    0.86                                          56        61             520    1.05                                          57        70             470    1.51                                          58        63             430    1.96                                          59        67             520    0.55                                          60        69             620    1.26                                          61        167            890    9.10                                          62        181            116    3.64                                          63        194            109    0.85                                          64        195            177    0.72                                          65        196            246    0.57                                          66        198            151    0.62                                          67        199            194    0.62                                          68        202            194    0.49                                          69        204            505    1.66                                          70        212            169    0.63                                          71        213            328    0.86                                          ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Photo-                                                                        Conductor Bisazo         Vpo    E1/2                                          No.       Pigment No.    (V)    (lux · sec)                          ______________________________________                                        72        58             594    5.80                                          73        90             856    5.86                                          74        115            212    6.84                                          75        163            358    6.13                                          76        16             310    4.23                                          77        65             762    5.92                                          78        59             420    4.47                                          79        60             790    5.92                                          80        71             420    1.85                                          81        72             284    1.33                                          82        63             543    8.39                                          83        67             475    1.79                                          84        179            812    3.31                                          85        180            962    3.25                                          86        172            442    1.95                                          87        174            333    2.07                                          88        173            650    7.41                                          89        2              628    6.53                                          90        33             206    2.43                                          91        181            280    6.71                                          92        192            268    10.61                                         93        189            292    10.82                                         94        193            868    12.88                                         95        194            527    6.70                                          96        195            279    2.77                                          97        196            960    5.06                                          98        198            778    3.95                                          99        199            994    2.63                                          100       201            236    1.76                                          101       202            570    6.37                                          102       207            242    1.26                                          103       208            159    0.61                                          104       209            554    1.79                                          105       210            283    4.83                                          106       211            272    1.69                                          107       212            332    5.10                                          108       213            568    4.94                                          ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Photo-                                                                        Conductor Bisazo         Vpo    E1/2                                          No.       Pigment No.    (V)    (lux · sec)                          ______________________________________                                        109       90             988    7.62                                          110       163            544    6.68                                          111       16             484    5.67                                          112       65             962    7.40                                          113       59             806    7.71                                          114       60             984    7.31                                          115       71             874    2.90                                          116       72             584    2.48                                          117       74             470    2.54                                          118       62             620    3.82                                          119       67             681    2.71                                          120       179            949    5.25                                          121       180            1187   4.49                                          122       172            693    3.38                                          123       174            704    3.38                                          124       181            364    5.83                                          125       42             1028   7.54                                          126       182            516    9.68                                          127       194            739    13.85                                         128       195            501    4.33                                          129       196            1082   8.51                                          130       198            996    5.38                                          131       199            766    3.93                                          132       200            297    3.29                                          133       201            421    3.97                                          134       202            785    9.01                                          135       203            506    2.17                                          136       205            456    1.22                                          137       206            247    3.16                                          138       207            531    2.97                                          139       208            565    1.65                                          140       209            794    2.90                                          141       210            415    9.12                                          142       211            693    3.32                                          143       212            402    7.34                                          144       213            958    6.35                                          ______________________________________                                    

Furthermore, the electrophotographic photoconductors No. 4 and No. 7according to the present invention were separately incorporated into acommercially available copying machine ("MYRICOPY M-5" made by RicohCompany Ltd.) and the image formation tests were repeated 10,000 times.As a result, both of the photoconductors No. 4 and No. 7 yielded clearimages without any degradation due to the deterioration of thephotoconductor in the course of the repeated operation.

To measure the spectral reflectance of the bisazo pigment for use in thepresent invention, the following sample No. 1 containing a bisazopigment for use in the present invention and comparative samples No. 2and No. 3 were prepared:

(1) Preparation of Sample No. 1

A mixture of 7.5 parts by weight of the bisazo pigment No. 58 for use inthe present invention, as listed in Table 1, and 500 parts by weight ofa tetrahydrofuran solution containing polyester resin (Trademark "Vylon200" made by Toyobo Co., Ltd) with a solid component of 0.5% wasdispersed and ground in a ball mill. The thus obtained dispersion wascoated by a doctor blade on an aluminum-deposited surface of a substratewhich was obtained by subjecting a polyester film toaluminum-deposition, and dried, so that a pigment-layer having athickness of 0.5 μm was formed on the substrate.

(2) Preparation of Samples No. 2 and No. 3

The same procedure as that employed in the above-mentioned preparationof sample No. 1 was repeated except that the-bisazo pigment No. 58 wasrespectively replaced by the following bisazo pigments, so thatcomparative samples No. 2 and No. 3 were prepared. ##STR465##

The spectral reflectance of the above-prepared samples No. 1, No. 2 andNo. 3 was measured using "Color Analyzer Type-607" made by Hitachi, Ltd.The results are given in FIG. 13.

As shown in FIG. 13, the sample No. 1 employing the bisazo pigment No.58 according to the present invention shows a lower spectral reflectanceeven in a long wavelength region, in comparison with the samples No. 2and No. 3. This indicates that the sample No. 1 has a sufficiently highabsorbance, in particular, in the long wavelength region, so that it isuseful in the electrophotographic process using semiconductor laserbeams.

Tables 5 to 8 indicate that the electrophotographic photoconductorsaccording to the present invention which contain the particular bisazopigments as charge generation material have high photosensitivity, andgood properties which do not change in the course of the repeatedoperation. In addition, the photoconductors according to the presentinvention can be manufactured more easily than conventionalphotoconductors.

What is claimed is:
 1. A charge generating material having the formula(I): ##STR466## wherein Ar in the formula (I) is ##STR467## wherein Xrepresents --OH, ##STR468## or --NHSO₂ --R³, wherein R¹ and R² eachrepresent hydrogen, an unsubstituted or substituted alkyl group; and R³represents an unsubstituted or substituted alkyl group or anunsubstituted or substituted aryl group;Y¹ represents hydrogen, ahalogen, an unsubstituted or substituted alkyl group, an unsubstitutedor substituted alkoxy group, a carboxyl group, a sulfo group, anunsubstituted or substituted sulfamoyl group, ##STR469## wherein R⁴represents hydrogen, an unsubstituted or substituted alkyl group, or anunsubstituted or substituted phenyl group; and Y² represents anunsubstituted or substituted cyclic hydrocarbon group, an unsubstitutedor substituted heterocyclic group, or ##STR470## wherein R⁵ representsan unsubstituted or substituted cyclic hydrocarbon group, anunsubstituted or substituted heterocyclic group, or an unsubstituted orsubstituted styryl group; and R⁶ represents hydrogen, an alkyl group, oran unsubstituted or substituted phenyl group, or R⁵ and R⁶ may form anunsubstituted or substituted ring in combination with a carbon atomlinked thereto; Z represents an unsubstituted or substituted cyclichydrocarbon group, or an unsubstituted or substituted heterocyclicgroup; n is an integer of 1 or 2; and m is an integer of 1 wherein X issituated ortho or para to the site of attachment of the azo group.
 2. Acharge generating material having the formula (I): ##STR471## wherein Aris ##STR472## wherein X represents --OH, ##STR473## or --NHSO₂ --R³,wherein R¹ and R² each represent hydrogen, or an unsubstituted orsubstituted alkyl group; and R³ represents an unsubstituted orsubstituted alkyl group or an unsubstituted or substituted aryl group;Y¹represents hydrogen, a halogen, an unsubstituted or substituted alkylgroup, an unsubstituted or substituted alkoxyl group, a carboxyl group,a sulfo group, an unsubstituted or substituted sulfamoyl group, or##STR474## wherein R⁴ represents hydrogen, an unsubstituted orsubstituted alkyl group, or an unsubstituted or substituted phenylgroup; and Y² represents an unsubstituted or substituted cyclichydrocarbon group, an unsubstituted or substituted heterocyclic group,or ##STR475## wherein R⁵ represents an unsubstituted or substitutedcyclic hydrocarbon group, an unsubstituted or substituted heterocyclicgroup, or an unsubstituted or substituted styryl group; and R⁶represents hydrogen, an alkyl group, or an unsubstituted or substitutedphenyl group, or R⁵ and R⁶ may form an substituted or substituted ringin combination with a carbon atom linked thereto; and Z represents anunsubstituted or substituted cyclic hydrocarbon group or anunsubstituted or substituted heterocyclic group.
 3. A charge generatingmaterial having the formula (I): ##STR476## wherein Ar is ##STR477##wherein X represents --OH, ##STR478## or --NHSO₂ --R³, wherein R¹ and R²each represent hydrogen, or an unsubstituted or substituted alkyl group;and R³ represents an unsubstituted or substituted alkyl group or anunsubstituted or substituted aryl group;Y¹ represents hydrogen, ahalogen, a substituted or unsubstituted alkyl group, an unsubstituted orsubstituted alkoxyl group, a carboxyl group, a sulfo group, asubstituted or unsubstituted sulfamoyl group, or ##STR479## wherein R⁴represents hydrogen, an unsubstituted or substituted alkyl croup, or anunsubstituted or substituted phenyl group; and Y² represents anunsubstituted or substituted cyclic hydrocarbon group, an unsubstitutedor substituted heterocyclic group, or ##STR480## wherein R⁵ representsan unsubstituted or substituted cyclic hydrocarbon group, anunsubstituted or substituted heterocyclic group, or an unsubstituted orsubstituted styryl group; and R⁶ represents hydrogen, an alkyl group, oran unsubstituted or substituted phenyl group, or R⁵ and R⁶ may form anunsubstituted or substituted ring in combination with a carbon atomlinked thereto: and Z represents an unsubstituted or substituted cyclichydrocarbon group, or an unsubstituted or substituted heterocyclicgroup.
 4. A bisazo compound having the formula: ##STR481## wherein Arrepresents ##STR482## wherein Y represents a methoxy carbonyl group; anN,N-dimethyl carbamoyl group; --CONH--Y¹ in which Y¹ represents anunsubstituted or substituted hydrocarbon group, or an unsubstituted orsubstituted heterocyclic group; or --CONH═CH--Y² in which Y² representsan unsubstituted or substituted hydrocarbon group, or an unsubstitutedor substituted heterocyclic group; and Z represents a benzene ring, anaphthalene ring, or an carbazole ring each of which rings may have asubstituent.
 5. The bisazo compound as claimed in claim 4, wherein saidbenzene ring, naphthalene ring and carbazole ring represented by Z mayhave a substituent selected from the group consisting of a halogen, analkyl group, and an alkoxyl group; said hydrocarbon group represented byY¹ is (i) a phenyl group which may have a substituent selected from thegroup consisting of an alkyl group, an alkoxyl group, a hydroxyl group,a dialkylamino group, a halogen, a nitro group, a phenylamino group anda phenylcarbamoyl group, or (ii) a naphthyl group which may have asubstituent selected from the group consisting of an alkyl group, ahalogen, a hydroxyl group, a nitro group and an alkoxyl group; or saidheterocyclic group represented by Y¹ is a group selected from the groupconsisting of a carbazolyl group, ##STR483## and said hydrocarbon grouprepresented by Y² is (i) a phenyl group or naphthyl group which may havea substituent selected from the group consisting of an alkyl group, analkoxyl group, a halogen, a hydroxyl group and a nitro group, or (ii) ananthryl group.